12 volt key on power source

[Weitzracing_369]

Hi guys, I’m installing a Holley Sniper Efi system on my 64’ imperial. Right now I’m trying to locate a good 12volt key on source. ( I need it to power on 12 volts when the key is turned to the key on position as well when the key is turned to crank engine over. I’m tracing wires as we speak, thought maybe one of you has already been through this. Thanks, Brian